3 replies so far

They have to be dried very very very slowly. Coat the end grain with Anchorseal (available at UC Coatings). Start outside in the ambient air under cover but not in a heated and cooled space. The humidity is too low and that will result in too rapid drying. After a four or five months outside under cover, you can bring them inside and let them continue to dry. Don’t be in a hurry, and cut a bunch more than you need to increase the odds that some will not crack or split. These are about the hardest thing to dry successfully without specialized equipment.

I think you might have to treat them as one would a green turned bowl. Look up some of the turners methods for preventing their bowls from splitting and that might work. LT15 is right that it has to be done slow and by that he means dead slow. You might even have to cover some in wax and put it away for a couple of years. Good luck

Polyethylene glycol (PEG) is a product sold under various brands that was designed for this purpose. You coat the wood well and it soaks in and somehow keeps it from cracking. I have also heard that using a 50/50 mix of Kirkland brand liquid dishwashing soap will do it too.